How to Make It
Preheat the oven to 325°. In a small bowl, mix the paprika with 1 teaspoon of salt and 2 teaspoons of black pepper and. Rub the seasonings all over the brisket. Heat the oil in a large roasting pan set over 2 burners. Add the brisket and cook over moderately high heat, turning once, until lightly browned on both sides, about 3 minutes per side. Transfer the brisket to a platter.
Add the onions and garlic to the pan and cook over moderately low heat, stirring, until softened, about 10 minutes. Add the stock, tomatoes, sherry vinegar, thyme, bay leaves, saffron and the sherry and bring to a boil over high heat. Return the brisket to the pan and cover tightly with foil. Braise in the oven for 3 hours or until tender, turning the meat once and basting it occasionally with the pan juices. Add the olives after the first 1 1/2 hours.
Transfer the brisket to a platter and cover with foil. Strain the pan juices into a large saucepan, reserving the olive-and-onion mixture. Spoon off the fat. Boil the juices until reduced to 3 cups, about 20 minutes. Return the olive-onion mixture to the saucepan and season with salt and pepper.
Thinly slice the brisket across the grain and return to the roasting pan, keeping the shape of the brisket intact. Spoon the pan juices on top. Cover with foil and braise for 25 minutes, until heated through and very tender. Serve the brisket in its juices.